156 PHYSIOLOGY. 



are as digestible before they are cooked as after, often more 

 so, as they are very frequently badly cooked. But many 

 foods in the raw state are unattractive, or even repellent, 

 whereas cooking usually develops an agreeable odor and 

 taste. Cooking should soften the harder and tougher tis- 

 sues, such as cellulose in vegetables, and the connective 

 tissue of animal foods. Cooking starch causes the starch 

 grains to swell and burst, and makes the starch much more 

 digestible. 



Making Soup. If meat be cut into small pieces and 

 put into cold water, and the water gradually warmed, the 

 soluble material of the meat may be extracted, and this is 

 the principle followed in making soups. 



Boiling Meat. But if we wish to cook the meat itself, 

 the juices should be retained instead of withdrawn. For 

 this purpose boiling water is poured over the meat to co- 

 agulate the outer layer, and prevent the extraction of the 

 juices. 



Baking, Roasting, and Broiling. The same principle 

 applies to baking, roasting, and broiling. The outside is 

 subjected to high heat at the beginning of the cooking, 

 which forms a layer nearly impervious to the nutritious 

 material inside. In these modes of cooking it is very de- 

 sirable to reduce the heat applied after the first few min- 

 utes, so that the interior may be more gradually cooked ; 

 this is, perhaps, especially true in broiling. 



Frying. Frying, as ordinarily done, is not a good 

 mode of cooking ; in fact, is often very bad, as the food is 

 frequently penetrated by fat and rendered very indigestible. 

 But true frying, that is, by immersion in boiling fat, is a 



